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APPROVED

General Manager

ASONIKA SRI, LTD

___________ A.S. Shalumov

12.03.2013

Subsystem analysis and thermal characteristics of hardware design in ASONIKA-T

_______________________

Application description

User’s Guide

Validated Page _____________________

146 pages

2013

Letter


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An Automated System for Ensuring the Reliability and Quality of Equipment

(ASONIKA)

SUBSYSTEM ANALYSIS AND THERMAL CHARACTERISTICS OF

HARDWARE DESIGN IN ASONIKA-T

APPLICATION DESCRIPTION

2013


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АСОНИКА Т. Описание применения

ANNOTATION

We review the issues of automated modeling of thermal processes with arbitrary

design of radio electronic means in models of thermal processes (MTP), built by the user.

The documents -- "Description of the subsystem", "User's Guide," and "System

Administrator's Guide" -- discuss the purpose and structure of the subsystem, the

subsystem description, use of the subsystem, the form’s data input, the methodology of

thermal design models and calculations of their thermal modes of radio electronic means,

configuration, and structure and launch of ASONIKA-T subsystem.

Subsystem ASONIKA-T is used within Russian Federation Ministry of Defense for

monitoring the correct application of electronic technology in special-purpose hardware. It

is recommended for the set of standards "MOROZ-6" for use in the process of design and

replacement testing in the early stages of design. On July 1, 2000, the following document

was enacted which was developed jointly with TNIII 22 of the Defense Ministry of

Russian Federation, KGTA, and MGIEM, regulating the use of the ASONIKA systemduring design: RDV 319.01.05-94 , Rev.2 -2000. Document Guide. Comprehensive

quality assurance system. Instruments, devices, and equipment for military purposes.

Principles of mathematical modeling during design / Y.N. Kofanov, A.S. Shalumov, A.I.

Andreev, V.G. Zhuravskii, V.V. Goldin, Y.I. Stepanov, A.A. Borisov. - M.: 22nd TNIII

Ministry of Defense, 2000. – 57pp.

In 2007, a certificate from the Russian Federation Ministry of Defense was obtained

for ASONIKA system, according to which the system met the requirements of the RDV

319.01.09-94 (eds. 2-2000) and is suitable for the automated control of the correct

application of RFC in the development of equipment for the benefit of the Russian

Defense Ministry.


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CONTENTS

1. 1. SUBSYSTEM DESCRIPTION .................................................................................................... 5

1.1. Use and technical specifications of the subsystem......................................................................... 5

1.2. Description of thermal models of the subsystem ......................................................................... 10

2. USER GUIDE ........................................................................................................................................ 12

2.1. Starting the subsystem and main menu items ............................................................................ 12

2.2. Forced water cooling design .......................................................................................................... 29

2.3. Natural air cooling design ............................................................................................................. 30

2.4. Modelling and simulation results interface ................................................................................. 31

2.5. Sources of influence and capacity modelling ............................................................................... 35

2.6. Demonstration of different power sources................................................................................... 64

2.7. Example of thermal modeling a floor cabinet ............................................................................ 66 2.7.1. Analysis of thermal processes ................................................................................................................................. 67

2.7.2. Simulation results .................................................................................................................................................... 71

2.7.3. Results ....................................................................................................................................................................... 73

3. SYSTEM ADMINISTRATOR'S GUIDE ........................................................................................... 74

3.1. Structure and launch of ASONIKA-T ......................................................................................... 74

3.2. Saving the project........................................................................................................................... 74

4. BASIC PRINCIPLE METHODS OF CONSTRUCTION OF THERMAL MODELS ................. 75

4.1. General information ...................................................................................................................... 76

4.2. "Heated zone" and the principle of local influence .................................................................... 78

4.3. Designation of MTP branches ...................................................................................................... 80

4.4. Properties of models in different coordinate systems ................................................................. 81

5. MODELS OF THERMAL PROCESSES FOR STANDARD DESIGNS AND REM ELEMENTS..................................................................................................................................................................... 82

5.1. Constructing an MTP plate with a heater of P power on one of the sides ............................... 82

5.2. Thermal process model of a transistor ......................................................................................... 85

5.3. Thermal process model of a transistor mounted on the radiator .............................................. 86

5.4. Thermal process model of an air channel (air-duct) .................................................................. 88

5.5. Thermal process model of a sealed REM block ......................................................................... 90

5.6. Thermal process model of a perforated REM block .................................................................. 95

5.7. Cartridge design of an REM block as a standard design element .......................................... 100 5.7.1. Cartridge block with an air flow .................................................................................................. ............................ 100

5.7.2. Sealed cartridge block ............................................................... .............................................................. ................. 104

5.8. Thermal processes model of an REM rack ................................................................................ 106

APPENDINX ........................................................................................................................................... 115


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1. 1. SUBSYSTEM DESCRIPTION

1.1. Use and technical specifications of the subsystem

Subsystem ASONIKA-T is designed to automate the modeling of thermal processes

of microassemblies, radiators, heat sinks, hybrid-integrated modules, blocks and stackable

cassette design, cabinets, racks, and other non-standard (arbitrary) structures.

The subsystem allows during the design of radio electronic means (REM) to

implement the following project objectives:

− determination of average temperatures of blocks, printed circuit boards, and

materials with design, as well as the volume of air within the REM;

−

modification to the REM design to achieve acceptable thermal conditions;

− selection of the best option in terms of thermal modes of design from several

existing conceptual options;

−

the rationale for the necessity and evaluation of effectiveness of additional protection of REM against thermal effects;

− creating effective testing models and prototypes of REM on thermal effects (the

objective of selection of most informative influences, the selection of sensors, and

establishment of points in most thermally loaded places, etc.).

The subsystem allows simulating steady and transient thermal modes of REM

placed in air environment, both in normal and under reduced pressure and cooled by

natural or forced convection. As a result of the simulation, the average temperature values

of selected isothermal air volume are determined, as well as average temperatures of

designs at lower levels for further thermal modeling, with the implementation of the "top –

down” design procedure. Thus, during thermal modeling of radio-electronic cabinets, the

average temperature values of the blocks or modules are determined; then the next step is

to model these block or modules. The result is the average temperature values for printed

circuit boards. Next, for thermal modeling of printed circuit boards, subsystem

ASONIKA-TM is used, which allows one to get the temperature field of each printed


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circuit board and each radioelement. By comparing radioelement temperature output

values with temperature limit values of these elements, we can determine compliance with

temperature margins, and thus we are able to detect overloaded radioelements. If the

requirements are met, then the temperature values of radioelements are transferred to

electrical calculation program to further confirm these calculations.

Temperatures of PCB components are required for mechanical calculations in

ASONIKA-TM.

Temperature fields along with average temperatures of standard design components

are determined in ASONIKA-T subsystem, which allow an opportunity to get a

preliminary understanding about thermal conditions and use this information in

ASONIKA-M subsystem to carry out complex mechanical modelling taking into account

temperature values.

ASONIKA-T program includes a database with reference geometrical and thermal

RFC parameters and design materials, graphical input of initial data, and graphical output

of calculated results.

To carry out simulation session using this subsystem requires the following background information:

− a sketch or drawing of the underlying REM design;

−

thermo-physical parameters of materials considered in REM design;

−

heat generation capacity in designs with a low level of hierarchy considered as

part of the design. Heat-generators, in the design, are made from mounted REM

radioelements;

−

cooling conditions (boundary conditions) of REM design.

The block diagram of the subsystem is shown in figure 1.1.


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Figure 1.1: Block diagram of ASONIKA-T subsystem

TeRa

Calculation module

Ac_t

Integrated database

Calculation results output

module

ShowGR

Information support

subsystem ASONIKA-T

Dialog of input parameters for

modelling thermal processnodes

Dialog of input parameters for

modelling thermal process

branches

Dialog of input parameters forMTP of standard elements

Dialog of standard elements

coupling for the general

model of thermal processes

Vectorization modellingmodule

Library of

standardelements

Database of

materials

Raw data files *.dat

Automated synthesis of

modelling standard elements

module

Results file *.rez

Help of ASONIKA-T

subsystem


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At its core lies Asonika_T, which has two main functions. Firstly, this module is a

managed wrapper for the subsystem and contains several modules and dialogs for

communication between various function subsystems while performing certain functions,

such as calculation processing, database query of materials and standard components, and

display of necessary user information. Secondly, this module is a graphical frontend for

the construction of the graph, the topological model of thermal processes. Through this

module, the user controls the entire information space of the subsystem. All control and

interaction with the user is done through the module using special dialogs.

Work with the subsystem starts with a model of thermal processes or a macromodel

of the investigated design. Each of these stages is reflected in the automated module

Asonika_T with a relevant dialog form. Construction of a model begins by defining the

nodes of topological graphs. For this purpose, there is a dialog form which guides the

user when inputting node parameters into the model. Further, the nodes are connected with

branches to define thermal coupling between elements of the design. For this process, too,

there is a dialog that asks the user for the branch type and the necessary thermal

parameters of the given influence. Thus, the model is constructed of any complexity.However, this process is inefficient and requires a lot of attention and labor to create the

model. For this reason Asonika_T module has been added with newly developed

algorithms and methods for automated MTP synthesis of standard elements. Standard

types of elements were created and methods and algorithms of automated synthesis were

developed for these elements. To construct a standard element MTP, simple and

understandable dialog forms are used for input of necessary parameters. Automatically

built MTPs are parameterized.

In addition, very often, construction of a complex model necessitates a use of

standard element of MTP couplings between one another in order to create a single model.

For these situations, required information is entered with the use of dialog forms to

automatically couple necessary elements of the design. These dialog forms greatly

simplify the work of the designer.

Modelling and display of topological models of thermal processes take place at the

same time for the investigated design. For this purpose a vectorization module is provided.


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This module is built using modern technologies of object-oriented programming and

implemented, as well as the entire subsystem, high-level language Delphi.

For automated synthesis of standard MTP elements, a synthesized model module is

created which builds a model based on set parameters using developed algorithms. The

final result of Asonika_T module is a source data file. Graphical information containing

the model is stored in a file with *.spt extension.

After a model is created, next step is to carry out the calculation. For calculations,

Ac_T.ex module is provided in the subsystem. Initial data used to carry out calculations is

stored in *.dat extension files. When the calculations are complete, the results are stored in

*.rez extension files. The results files are conveniently stored in a separate Result folder

located in the root directory of the subsystem. The presence of files containing graphics

and initial data in the root directory is required to successfully carry out calculations.

Depending on calculation results, the user is able to get a variety of textual and

graphical information. For this purpose, ShowGR module was developed to display results

for steady-state calculations shown in the nodes temperature table, as well as transient

calculations shown in a plot as node temperature vs time, and the nodes temperature tableat each time interval.

In addition, the subsystem provides a clear and extensive help system which in an

intelligible form explains how to work with the subsystem and to create models of thermal

processes.

To make it more convenient working with dialog forms in ASONIKA-T subsystem,

the program provides a functional relationship with an integrated data bank. The data bank

contains a set of databases that include background information about REM materials with

all thermo-physical parameters needed to carry out calculations. In addition, there is a

database of standard elements which can be replenished with elements created by the user.

It should be noted that the database is centralized and uniform for ASONIKA-T and

ASONIKA-TM subsystems. This makes it more effective during thermal analysis of an

integrated examination of components ranging from a supporting structure to a PCB,

where the results of one analysis are boundary conditions in the other.


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1.2. Description of thermal models of the subsystem

The subsystem allows modelling of steady-state and transient thermal processes of

REM design for different cooling conditions by forming a system of nonlinear algebraic

equations (for steady-state thermal process) or a system of ordinary differential equations

(for transient thermal process) to specify geometrical and thermal parameters of the REM

design. Design nodes and elements are specified in REM as well. Boundary conditions are

set by design to solve a system of equations. Output of results is carried out in a

convenient form for further analysis.

The system of equations which is formed by the subsystem is based on the

topological model constructed by the user and displayed on the computer screen.

To solve this problem, criterial equations from similarity theory and heat transfer

equations are used which include a method of nodal potentials which form mathematical

models of thermal processes as a system of ordinary differential equations (SODE) or asystem of nonlinear algebraic equations (SNAE).

Backward differentiation method is used to solve SODE; simple iteration method is

used to solve SNAE; and LU -decomposition method with symbolic factorization

accounting for a stiffening matrix for thermal conductivity is used to solve a system of

linear algebraic equations (SLAE) which are reduced from SODE and SNAE (at each time

step and/or at each iteration by nonlinearities).

Unlike other kinds of models, topological models of thermal processes set boundary

conditions of different kinds with REM design combinations of volumes and surfaces in a

simple way with the help of appropriate graphical components (branches, specified

temperature sources, and (or) thermal input sources).


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2. USER GUIDE

2.1. Starting the subsystem and main menu items

Starting the subsystem and main menu items. The subsystem is called with the

TeRa.exe command. When the program is launched, the subsystem’s window appears

which can be divided into three areas: the workspace – where topological model of

thermal processes (MTP) of the design is built, main menu, and the toolbar. These areas

are shown in Fig. 2.1.

Figure 2.1: Window of the subsystem

Main menu consists of the following set of commands: File, Edit, View, Design,

Analysis, Results, and Help shown in figure 2.2.

Figure 2.2: Main Menu

File menu, expanded in figure 2.3,


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Figure 2.3: File menu

provides the following features:

−

create a new model (item menu “File/New”);− load an already drawn model from the drive (item menu “File/Open”);

−

save a drawn model in a file on the disk (item menu “File/Save” or “Save As”);

−

finish working with the program (item menu “File/Exit”).

The initial data and simulation results are saved in the Data directory. No additional

directories and subdirectories for inputs and results are necessary. All files related to the

project have different extensions, but the same name.

Edit menu allows you to work with a database of thermal parameters of materials

and a database of coefficients for lubricants; save a part of a thermal model as a standard

element; load a standard element; as well as highlight an entire model.

Figure 2.4: Edit menu

View Menu causes parameter settings window to appear (figure 2.5), as well as a

display of a full model in a separate window.


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Figure 2.5: Edit menu and Options window

Design menu allows to choose a standard design shown in figure 2.6.

Figure 2.6: Design menu

Analysis menu allows to carry out calculations of the presented model, select

calculation parameters (steady-state and transient), and also enter a table of specific values

which vary according to the preset rules (figure 2.7).

Figure 2.7: Analysis menu


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Results menu allows (see figure 2.8):

Figure 2.8: Results menu

−

display a table of temperatures at each node of a model for a steady-state type

calculation; and display a table of temperatures at each node of a model at each time

interval for a transient type of analysis (this results table can also be saved to a text file);

−

display a temperature graph over time for a transient type of analysis;

−

display a table of temperatures at each node of a model at a given moment in time

under transient type of thermal analysis (you can also save to a file).

Help menu allows you to get help information about the program (figure 2.9).

Figure 2.9: Help menu

Before adding a thermal design model, one should be familiar with the method of

REM thermal model construction which is part of ASONIKA-T subsystem.

Toolbar consists of a set of buttons to invoke the main commands of the subsystem.

This menu is divided into three areas: Standard, Tools, and Options, each of which is

designed to perform a specific set of commands.


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Standard Toolbar (figure 2.10) contains buttons for the standard functions to work

with files, duplicates File menu item. Furthermore, it contains a button to view the original

data file .

Figure 2.10: Standard Toolbar

Tools Toolbar (figure 2.11) contains buttons which are used to create and edit

topological models of thermal processes, as well as a help button. Commands contained in

this toolbar will be reviewed in more detail below.

Figure 2.11: Tools Toolbar

Options Toolbar (figure 2.12) contains buttons which are used to retrieve

additional information about nodes and branches of a topological MTP design, as well

as the use of calculation parameters.

Figure 2.12: Options Toolbar

Working with GUI mathematical thermal model input of REM design in a

topological form begins with the introduction of numbered nodes into the model. To do

this, press the button in the toolbar. After that, set the cursor anywhere in the

workspace and press the left mouse button. You will be prompted to enter the number and

name of the node (see figure 2.13).


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Figure 2.13: Creating a topological thermal model node

Node numbering is automatic, however, the node number can be changed manually. Nodes must be numbered sequentially and without gaps.

Removing a node. Before removing the node, we need to remove all branches

which are connected to it. After that, we press the button in the toolbar. When the

cursor is placed on the node, press the left mouse button while holding down the Ctrl key.

The node will turn blue. Next, we click on the button. The node will be removed.

Creating a branch for a topological thermal model is carried out between two

nodes. To do this, click on the button in the toolbar. Select both nodes sequentially.

Next, select the branch type (figure 2.14).

Figure 2.14: Selecting branch type


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Next, enter the parameters of the corresponding branch, for example, a branch

representing radiation is shown in figure 2.15.

Figure 2.15: Branch parameters for radiation

As a result, we obtain the following pictorial representation (see. Fig. 2.16):

Figure 2.16: Representation of a radiation branch

“Power Source”, “Temperature Source”, and “Heat Capacity” branches are set only

for transient thermal calculations and are connected to one end of the node which has a

zero potential.

Removing a branch. To do this, click on the button in the toolbar. Then set the

cursor on a branch which needs to be removed, and click on the left mouse button while

holding down the Ctrl key. The branch will turn blue. Next, click on the button to

remove the branch.

Editing branch parameters. To do this, click on the button in the toolbar.

Next, set the cursor on a branch whose parameters need to be changed, and click on the


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right mouse button while holding down the Ctrl key. After that the window prompt will

appear where branch parameters can be edited.

Selecting an object. To do this, click on the button in the toolbar. Then, press

the left mouse button and outline the object with a rectangle. After the left mouse button is

released, the object will turn blue. Thus, the object will get highlighted. After that, the

entire object can be moved or deleted.

Moving nodes and objects is accomplished when button is selected in the

toolbar. Then, set the cursor on the thermal model node or object, which needs to be

moved, and then holding down the left mouse button, the item is moved. After the node is

moved, we first click on the button, and then choose a different one in the toolbar, for

example, the button.

Viewing node names and branch numbers. For this, the button is selected for

the first case, and button for the second.

Creating a library of standard elements. Very often in a physical thermal model

design there are standard, highly repetitive, elements. In order to avoid entering these

elements every time, we would need to save them once, and then insert them into each

new physical model when necessary. To save the newly created standard element, we first

select it (please see “Selecting an object” from above). Then, clicking on the right mouse

button and holding down Ctrl key select “Save as a standard component” from the prompt

menu. Saving the file (having uel file type) can be done in any directory which was

previously created, where all physical models of standard elements will be stored.Reading the standard element and inserting it into a physical model is achieved by

first selecting the button. Pressing the right mouse button while holding down Ctrl key

select “To insert typical element / Load a Standard Component” from the menu, and select

the uel file from the directory where models of standard elements are stored.

Physical models of standard elements are created by the program developers of

the subsystem. Currently, there are 4 types of standard REM design: plate, package,

modular design, and stack design.


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To insert a plate, select the button in the toolbar. Then, set the cursor anywhere

in the workspace and click on the left mouse button. In the window that appears (figure

2.17), we enter plate parameters.

Figure 2.17: Parameters window for a standard element “Plate”

After entering appropriate parameters, the screen will display an image of the

physical model of the plate (figure 2.18a). If you move the cursor to the plate and press the

right mouse button, a menu appears, prompting you to select one of the following: unfold

a physical model of the plate into a topological model or change plate’s parameters. When

the physical model of the plate is unfolded, the topological model will be displayed (figure

2.18b).

а)


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b)

Figure 2.18: Representation of a plate model:

a - physical; b - topological

The topological model of the plate can be “folded” by pressing the right mouse

button. To remove the plate, click on the left mouse button while holding down the Ctrl

key. The plate will turn blue, which means it is ready to be removed. Next, click on the

button. The plate will be removed.

When constructing the model of the plate, the principle of elementary zone

decomposition is used, within which the temperature distribution of the surface is

considered constant. The plate is divided into elementary provisional grid zones. Figure

2.18b shows an MTP plate taking into account heat distribution along the plate itself, as

well as convection of the environment and radiation on the adjacent elements or housing

walls of a block.

As can be seen from practice, there are two possible uses of an MTP plate. In

general, when the plate is used under normal conditions, convection and radiation


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branches are used, like the one shown in figure 2.18b. In a particular case, when a given

model describes operational conditions in a vacuum, we only show radiation.

In all of the above described cases, the use of an MTP gives the same initial

conditions. Primarily, we input the dimensions of the partition of the OX and OY axes,

that is the grid is discretized and thus we create the number of elementary zones. By

default, the temperature is the same in each zone but can be changed if necessary. Next is

given the overall size in millimeters. The second step is the selection of the number of

planes, operational conditions, namely the presence of the medium of the environment or a

vacuum, after which we set basic thermo-physical parameters: the path length of thermal

flow, thermal conductivity of the material, the emissivity of the surface, the irradiance

factor, critical size, orientation ratio, and the ambient pressure of the environment.

To input “Package” as a standard element, click on the button in the toolbar.

Next, place the cursor anywhere in the workspace and press on the left mouse button. In

the window which appears (figure 2.19), we enter appropriate parameters of the package.

Figure 2.19: Parameters window of a standard element “Package”

After all of the appropriate parameters are entered, the representation of a physical

model of the package will appear (figure 2.20а).


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а)

b)

Figure 2.20: Representation of the package model:

а - physical; b – topological

If you move the cursor to the package and press the right mouse button, a menu

appears, prompting you to select one of the following: unfold a physical model of the

package into a topological model or change parameters of the package. When the physical

model of the package is unfolded, the topological model will be displayed (figure 2.20b),

which can be folded back by clicking on the right mouse button.

To remove the package, click on the left mouse button while holding down the Ctrl

key. The package will turn blue, which means it is ready to be removed. Next, click on the

button. The plate will be removed.

This model element can be used to create virtually any REM design. To construct an

MTP block design, we must, in accordance with the principles of construction of

topological models, divide the model into basic elements. We highlight six basic

elements: front wall, back wall, upper wall, bottom wall, left wall, and right wall. But for

model construction, it is necessary to have nodes that represent the medium of theenvironment and the air inside the housing. Therefore, the MTP of the package will be

represented in the form of a disconnected graph consisting of eight nodes and appropriate


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branches (figure 2.20b). As in the case of a plane design, the given model will depend on

the medium of the environment, in which the block design will operate. Figure 2.20b

shows a block model in the environment. If the package is used in the vacuum, then

convection branches will be missing in the model. In that case, the influences between the

elements of the block will only be due to radiation. Each node of the design has its own

number. Each node represents one element of the design, that is: 1 - left wall, 2 – upper

wall, 3 – front wall, 4 – bottom wall, 5 – back wall, 6 – right wall, 7 – medium, and 8 –

inside air.

A standard REM element design labeled as “Modular Design” is also present in

ASONIKA-T subsystem. It is a set of modules which consist of two or three layers: the

middle one is aluminum, while a circuit board is attached to both sides or just one side is

attached to aluminum layer. Fins are located along the edges of the aluminum layer.

Because the fins are tied, the package is formed automatically as a result of tightening of

modules by the bolts. We only need to fix the two lids – one on top, and the other on the

bottom.

To create a standard “Modular Design”, select “Design/Modular Design” in themain menu. Next, set the cursor anywhere in the main window of the subsystem and click

on the left mouse button. In the dialog windows which appear (figure 2.21а and 2.21b) we

enter appropriate parameters for the design of the module.

а)


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b)

Figure 2.21: Dialog windows for entering parameters of a standard modular design

After entering all appropriate parameters, a physical model of a modular design will

appear in the main window of the subsystem in the “folded” form (figure 2.22а). If we

move the cursor to the package and the plate, by clicking on the right mouse button we can

“unfold” the package and the plate or edit the parameters of the package and the plate.

When the package and the plate are “unfolded”, a mathematical model of the topological

form (figure 2.22b) appears, which can be folded back to the physical form by clicking on

the right mouse button.

а)


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b)

Figure 2.22: Representation of modular design models:

а – physical mode; b – topological model

To remove the package and the plate, click on the left mouse button while holding

down Ctrl key. The package and the plate will turn blue. This means that they are ready to

be removed. Next, click on the button. The package and the plate will be removed.

The macromodel of the module can be represented in a simplified form as a package

model with the two inserted circuit boards (figure 2.22а). In the unfolded form, the

macromodel is shown in figure 2.22b. As shown in the figure, the model consists of a

package, nodes 1, 2, 3, 4, 5, and 6. These nodes represent the walls of the housing which

interact with the medium (node 7) through radiation. Since this design is primarily used in

the space industry and is operated in a vacuum, the convective heat transfer with the

environment is not present. However, if necessary, it is easy to add appropriate branches.

The internal structure of the package module represents a layer, node 7, which is

connected to the upper, lower, front, and back walls of the package. Circuit boards are

attached on both sides of the layer which are represented as multipoles in the macromodel.

The main heat source elements are the circuit boards. For more accurate modeling, they

are represented as plates broken down into four areas. Each plate has its own heat source.

These circuit boards, nodes 8 – 11 and 13 – 16, interact with air (nodes 12 and 17) through

radiation between the walls of the package and the circuit board and through conduction

with the layer.


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The design can contain up to fifteen modules connected into one design. The

package modules are connected with each other through conduction branches by wall

contact. Since the modules are bolted together, heat dissipation will be taken into account

due to these attachments. By increasing the number of modules in the design, conductive

branches will be added along adjacent, in direct contact with each other wall of the

modules. The rest of the parts of the macromodel will remain unchanged. In addition, you

can set radiation power for heat areas in the folded form or load directly to nodes of the

PCB in the unfolded form of the macromodel.

Let’s review a standard “Stack Design” which is a rectangular enclosure with circuit

boards of the same dimension stacked parallel to each other.

To create the stack design, select “Design/Stack Design” in the main menu. Next,

set the cursor anywhere in the main window of the program and click on the left mouse

button. In the dialog window which appears (figure 2.23) we set appropriate parameters of

the stack design.

Figure 2.23: Dialog window for entering parameters of the stack design


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After all appropriate parameters are entered, an image representing a folded form of

a physical model of the stack design will appear (figure 2.24а). If we set the cursor next to

the enclosure and click on the right mouse button, the window will appear that would

enable us to unfold the physical model of the stack design or change the parameters of a

standard stack design. When the enclosure is unfolded, the image of the topological model

will appear (figure 2.24b), which we can fold back by clicking on the right mouse button.

To remove the stack design, click on the left mouse button while holding down Ctrl

key. The model will turn blue, which means it is ready be removed. Next, click on the

button. The model will be removed.

а)

b)

Figure 2.24: Representation of a standard “Stack Design” model:

а – physical model; b – topological model

When working with an MTP stack design of an REM, it is necessary to consider

two cases:

−

forced convection cooling design (air flow between block’s circuit boards);− natural convection cooling design.

In both cases, the MTP of these designs have to let define:


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−

the temperature of the housing of the block;

−

average surface temperatures of circuit boards;

− air temperatures between printed circuit boards. For a natural convection cooling

design – average volume temperature of each air volume. For forced convection cooling

design – air temperature at the outlet of each air channel between printed circuit boards

and an average temperature of each air channel. These integral thermal condition

parameters of such designs are necessary in the future for a detailed analysis of thermal

REM characteristics, i.e. for the implementation of a hierarchical approach to modelling of

REM thermal processes.

Note that from the thermal processes perspective, both stack and cartridge designs

are virtually indistinguishable from each other. This allows for identical MTP analysis.

In ASONIKA-T 5.0 version, the user has an ability to automatically build thermal

models of standard radiators. Its functional use is described in the Appendix 2 of the

manual.

2.2. Forced water cooling design

We adopt the following idealization for the considered design in terms of heat

transfer processes:

− the surface of each printed circuit board is isothermal;

−

the surface of the housing block is isothermal;

−

heat flux from printed circuit assemblies through connectors and mounting wires

is negligible.

For an idealization to become acceptable, the following types of heat transfer are

available:

−

thermal influences through conduction between each printed circuit assembly and

the enclosure of the block;

−

thermal influence through conduction between the walls of the enclosure;


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−

radiation from the surface of the enclosure into the environment;

−

convective heat transfer from the surface of the printed circuit assemblies into the

airflows which pass in between;

−

convective heat transfer from the surface of the enclosure into the environment;

−

heat and mass transfer of air in the air channels between printed circuit

assemblies.

2.3. Natural air cooling design

Simplifications adopted in the idealization of heat exchange processes for the

considered designs are analogous to those listed above for a forced cooling design. The

following types of heat transfer exist for an idealized design:

−

radiation from each printed circuit assembly into the air between the printed

circuit assemblies;

− radiation from the surface of the enclosure of the block into the environment;

−

convective heat transfer from the surface of each printed circuit assembly into theair between the printed circuit assemblies;

− convective heat transfer from the areas of the inside surface of the enclosure,

restricted by the printed circuit assemblies, into the air;

−

convection from the surface of the enclosure of the block into the environment.

− thermal interaction by conduction between walls of the enclosure;

− thermal interaction by conduction between printed circuit assemblies and the

walls of the enclosure;

Figure 2.24b shows the described types of heat transfer and the accepted

idealization of an MTP stack design. The following notation is used in the MTP:

- nodes 1 through 6 – walls of the enclosure;

- nodes 9, 11, 13, 15 are printed circuit assemblies;

- nodes 8, 10, 12 , and 14 – air volume between printed circuit assemblies;

- node 7 – ambient environment.

- Р1 through Р4 – power of the thermal radiation of printed circuit assemblies.


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2.4. Modelling and simulation results interface

Once the topological model is created, it needs to be saved by clicking on the

button in the toolbar. You will be prompted to save the file with a .dat extension. Next, we

need to select the type of modelling – stationary or transient. For transient type of

modelling, we need to enter the appropriate parameters by clicking on the button (see

figure 2.25).

Figure 2.25: Modelling parameters of thermal processes

After, we can go to the “Analysis” in the main menu and click “Run”.

The source data can be reviewed in text format by clicking on the button. If

some parameters were edited, fast recalculation is available. However, these changes

won’t be saved in the original source data.

For stationary results of thermal analysis type, by selecting “Results” in the main

menu and then “Show Temperature at the Nodes”, the following will appear :


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−

nodes temperature table of the model (figure 2.26).

Figure 2.26: Nodes temperature table of the model

If necessary, the results can be saved in the text file by clicking on the “Save file”

button. The dialog window for saving a file will appear. The file will be saved with a .txt

extension in the Data directory. It is only necessary to specify just the name of the file.

For transient results of thermal analysis type, selecting “Results” in the main menu and

then “Plot Temperature vs. Time” submenu, will display:

− temperature graph over time under transient conditions (figure 2.27).


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Figure 2.27: Temperature graph over time under transient conditions

It is possible to configure the settings of the appearance of the plot. For example, if

we need to configure the appearance for node 1, double click on the “Node 1” label in the

“Model Nodes Selection” window (figure 2.28).

Figure 2.28: Nodes selection of the model, for which temperature plots over time under

transient conditions will be created


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Next, “Appearance settings configuration for Node 1” window will appear (figure

2.29), where we can select the plot color, style parameters color and background by double

clicking, select plot width, style, and height and width of the marker from the drop-down

box;

Figure 2.29: Appearance settings configuration

display nodes temperature table over a given time under transient conditions (figure

2.30).

−


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Figure 2.30: Nodes temperature table over a given time under transient conditions

If necessary, the results can be saved in text form by clicking on the “Save…”

button. The file will be saved with a .txt extension in the Data directory. It is only

necessary to specify the name of the file.

The method of creating thermal models is described in Appendix 1. Appendix 2 has

the types of branches and different parameters necessary for modelling.

2.5. Sources of influence and capacity modelling


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1.

Power sources.

1.1.

A source with constant power is created in the following way:

1.1.1. A special (base) node, with a zero label, is inserted into the model.

1.1.2.

Click on the button to select a branch type (the branch type number is

101).

1.1.3. The nodes are clicked on sequentially: first, the intended power source (node

1 in figure 2.31), then the base node (node 0).

Figure 2.31: Selecting a constant power source.

1.1.4.

Select “Power Source – constant”.

1.1.5.

In the dialog window which appears, we select the value of the dissipated

power source (figure 1.1.2).

Figure 2.32: Dialog window to set the value for the power source.


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1.1.6.

As a result, the constant power source is defined in the model (figure 2.33).

Figure 2.33: Constant power source specified at 20 W.

1.2. Time dependent power source (function).

1.2.1.

Initial steps, necessary for a power source selection with a specified function,

are analogous to figures 2.31, 2.32, 2.33. However, now we select “Power Source – time

dependent function” from the drop-down menu (figure 2.34, branch type number 103)

Figure 2.34. Time dependent power source selection specified by a function.

1.2.2. ASONIKIA-T allows for an input of several types of functions to set power

dependence on time: pulse, sinusoidal, sawtooth, and complex. Selection of an appropriate


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type is done from the drop-down box by clicking on the left mouse button and choosing

the function from the “Function Type” list (figure 2.35).

Figure 2.35: Selection of time dependent power types.

Each function has its own set of characteristics. For convenient determination, they

are shown as either prototype graphs under the drop-down list or as a formula.

1.2.2.1.

Impulse function (figure 2.36) allows you to simulate power sources withtwo states. For example, on / off or open / closed, etc. Time is expressed in second,

power in watts.

Parameter t0 – specifies an initial displacement of the 0th point. In the case of a

positive value, the lag in the function graph is specified. When a negative value is

specified, time duration and parameter value F2 increase.

Parameter F1 – specifies minimum value of the impulse.

Parameter F2 – specifies maximum value of the impulse.

Parameter t1 – specifies the time when the jump occurs relative to the stationary

nought (excluding t0).

Parameter t2 – specifies a full period of the impulse.


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Figure 2.36: Time dependent power source set by the impulse function.

1.2.2.2. Sinusoidal function (figure 2.37).

Parameter А – specifies the constant component in Watts.

Parameter B – specifies the amplitude of power oscillations.

Parameter W – determines the frequency of oscillation, where t - time in seconds.

Parameter df – phase shift.

Figure 2.37: Time dependent power source set by sinusoidal function.

1.2.2.3.

Sawtooth function (figure 2.38).


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Figure 2.38. Time dependent power source set by the sawtooth function.

Parameters are analogous to the impulse function, the only change is in the

characteristic of the dependent variables. The peaks and troughs occur gradually without

any sudden changes.

1.2.2.4.

Complex function (figure 2.39).

Figure 2.39: Time dependent power source set by the complex function.

This function represents itself as a more complex impulse function, here the

transition from a minimum to a maximum occurs gradually and not immediately.


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The initial point is specified with t0 and F1 parameters. Next, the value of the power

increase to F2 during time t0 - t1. From t1 to t2, the values stay the same and equal to F2.

From t2 to t3, the values decrease until they reach F1 and stay constant again from t3 to t4.

1.3.

Time dependent power source (table).

1.3.1. Select “Analysis” from the main menu, and then select “Table” (figure 2.40).

Figure 2.40: Selecting “Table” from the main menu.

1.3.2.

When the tables window appears, right-click and select “New Table” (figure

2.41).

Figure 2.41: Adding a new table.

1.3.3.

In the dialog window, specify the name of the table (figure 2.42).


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Figure 2.42: Specifying the name of the table.

1.3.4.

Fill in the table in accordance to the appropriate functional relationship

(figure 2.43).


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Figure 2.43: Filling out the table.

1.3.5. Switch to the model’s nodes. Initial steps necessary for power source

selection entered with the table are similar to the steps specified in figures 2.31, 2.32, 2.33.

In the drop-down window, select “Power Source – Time-dependent (Table) (figure 2.44,

branch type number 102).


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Figure 2.44: Time dependent power source selection entered with the

table.

1.3.6.

In the drop-down box, choose appropriate table number (figure 2.45).

Figure 2.45: Window for selection of a table.

1.3.7.

The power source is defined (figure 2.46).

Figure 2.46: Specified power source.


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2.

Temperature source.

2.1. Constant temperature source is set in the following way:

2.1.1.

A special (base) node with a zero numeral is entered into the model.

2.1.2. Click on the button to select the appropriate branch type (branch type

number 111).

2.1.3.

The nodes are clicked sequentially: the intended temperature source is

selected first (node 1 in figure 2.47), and then the base node (node 0).

Figure 2.47: Constant temperature source selection

2.1.4. Select “Temperature Source - Constant”.

2.1.5. In the appearing dialog window, we specify the value of the temperature

(figure 2.48).


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Figure 2.48: Use of the dialog window for inputting the value of the

temperature source

2.1.6.

As a result, the constant temperature source is defined in the model (figure

2.49).

Figure 2.49: Constant temperature source of 200С

2.2.

Time dependent temperature source (function).

2.2.1.

Initial steps necessary for selecting a temperature source with a function are

analogous to the steps shown in figures 2.47, 2.48, 2.49. But now we select “Temperature

Source – Time-dependent (Function)” from the drop-down menu (figure 2.50, branch type

number 113)


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Figure 2.50: Selecting time dependent temperature source with a function.

2.2.2. ASONIKA-T lets users to input several types of functions to define

temperature dependence from time: pulse, sinusoidal, sawtooth, and complex. Selection of

an appropriate type is done by clicking on the left mouse button in the “Type of function”

drop-down box and choosing from the (figure 2.51).

Figure 2.51: Time dependent temperature type selection.

Each function has its own set of characteristics. For a convenient definition, they are

shown as prototype graphs under the drop-down list or as a formula.


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2.2.2.1.

Impulse function (figure 2.52) lets the user model temperature source with

two states. For example, on / off, open / closed, etc. The time is in seconds, the

temperature is in degrees Centigrade.

Parameter t0 – specifies an initial displacement of the 0th point. In the case of a



Parameter F1 – specifies minimum value of the impulse.

Parameter F2 – specifies maximum value of the impulse.



Parameter t2 – specifies full period of an impulse.

Figure 2.52: Time dependent temperature source with an impulse function.

2.2.2.2.

Sinusoidal function (figure 2.53).

Parameter А – specifies the constant component of the temperature in degrees

Centigrade.

Parameter B – specifies the amplitude of temperature oscillations.

Parameter W – defines frequency of oscillations, where t is in seconds.



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Figure 2.53: Time dependent temperature source with a sinusoidal function.

2.2.2.3. Sawtooth function (figure 2.54).

Figure 2.54: Time dependent temperature source with a sawtooth function.

The parameters are analogous to the ones in the impulse function. The only change

is in the type of dependence. The function values transition from the minimum to

maximum, without sudden jumps, gradually.

2.2.2.4. Complex function (figure 2.55)


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Figure 2.55: Time dependent temperature source with a complex function.




increases to F2 during time t0 - t1. From t1 to t2, the values stay the same and equal to F2.


2.3. Time dependent temperature source (table).

2.3.1.

Select “Analysis” from the main menu, and then select “Table” (figure 2.56).


2.3.2.

When the tables window appears, right-click and select “New Table” (figure

2.57).


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Figure 2.57 Adding a new table.

2.3.3.

Specify the name of the table in the dialog (figure 2.58).


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Figure 2.58: Entering the name of the table.

2.3.4. Fill in the table in accordance to the appropriate functional relationship

(figure 2.59).


2.3.5. Switch to the model’s nodes. Initial steps necessary for temperature source

selection with a table are similar to the figures shown in 2.47, 2.48, 2.49. Select

“Temperature Source – Time-dependent (table)” in the drop-down menu (figure 2.60,

branch type number 112).


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Figure 2.60: Selection of time dependent temperature source with a table.

2.3.6. Select the table number from the dialog window (figure 2.61).

Figure 2.61: Window used for selecting the table.

2.3.7. The temperature source is defined (figure 2.62).

Figure 2.62: Defined temperature source.


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3.

Heat Capacity.

3.1.

Constant heat capacity is set the following way:

3.1.1. A special (base) node is entered into the model.

3.1.2.

Click on the button to select the branch type (branch type number 121).

3.1.3. The nodes are selected sequentially: the expected heat capacity first (node 1

in figure 2.63), then the base node (node 0).

Figure 2.63. Constant heat capacity selection.

3.1.4. Select “Heat Capacity - Constant”.

3.1.5.

In the dialog window, specify the value of the heat capacity (figure 2.64).

Figure 2.64: Dialog window for setting heat capacity value.


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3.1.6.

The heat capacity is defined in the model (figure 2.65).

Figure 2.65: Setting heat capacity to 0.01 J/K.

3.2.

Time dependent heat capacity (function).

3.2.1.

Initial steps necessary for heat capacity selection are analogous to the figures

shown in 2.63, 2.64, 2.65. But now, we need to select “Heat Capacity – Time-dependent

(Function)” from the drop-down menu (figure 2.66, branch type number 123)

Figure 2.66: Time dependent heat capacity set with a function.

3.2.2.

ASONIKA-T lets users set several types of functions for the definition of heat

capacity dependence from time: pulse, sinusoidal, sawtooth, and complex. To select an


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appropriate type, click on the “Function Type” drop-down box and choose one from the

list (figure 2.67).

Figure 2.67: Time dependent heat capacity selection.

Each function has its own set of characteristics. For convenient definition, they are

shown as a prototype graph under the drop-down list or as a formula.

3.2.2.1.

Pulse function (figure 2.68) lets modelling heat capacity with two states.

For example on / off, open / closed, and so on. The time is set in seconds, the heat capacity

is in Joules per Kelvin.

Parameter t0 – specifies an initial displacement of the 0th

point. In the case of a



Parameter F1 – specifies a minimum value of the impulse.

Parameter F2 – specifies a maximum value of the impulse.



Parameter t2 – specifies the full period of the impulse.


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Figure 2.68: Time dependent heat capacity with a pulse function

3.2.2.2. Sinusoidal function (figure 2.69).

Parameter А – sets a constant component of the heat capacity in Joules per Kelvin.

Parameter B – sets an amplitude of heat capacity oscillations.

Parameter W – defines frequency of oscillations, where t is in seconds.


Figure 2.69: Time dependent heat capacity with sinusoidal function

3.2.2.3.

Sawtooth function (figure 2.70).


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Figure 2.70: Time dependent heat capacity set with the sawtooth function.

Parameters are analogous to the pulse function. Only character dependence is

different. The function transitions from the minimum value to the maximum and vise versa

gradually and not suddenly.

3.2.2.4. Complex function (figure 2.71)

Figure 2.71: Time dependent heat capacity set with the complex function.


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increases to F2 during time t0 - t1. From t1 to t2, the values stay the same and equal to F2.


3.3.

Time dependent heat capacity (table).

3.3.1.

Select “Analysis” from the main menu, and then select “Table” (figure 2.72).


3.3.2. When the tables window appears, right-click and select “New Table” (figure

2.73).

Figure 2.73: Adding a table.


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3.3.3.

Enter the name of the table in the dialog window (figure 2.74).

Figure 2.74: Entering the name of the table.

3.3.4.

Fill out the table in accordance with the appropriate dependence relationship

(figure 2.75).


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3.3.5. Switch to the model’s nodes. Initial steps necessary for heat capacity

selection are analogous to the steps shown in figures 2.63, 2.64, 2.65. In the drop-down

menu, select “Heat Capacity – Time-dependent (Table)” (figure 2.76, branch type number

122).


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Figure 2.76: Time dependent heat capacity set by a table.

3.3.6.

In the dialog window, choose the number of the table (figure 2.77).

Figure 2.77: Window for table selection.

3.3.7. The heat capacity is defined (figure 2.78).


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Figure 2.78: Defined heat capacity.

3.4.

Calculated heat capacity.

3.4.1.

Select heat capacity according to figures 2.63, 2.64, 2.65. In the drop-down

menu, select “Heat Capacity - Calculated” (figure 2.79, branch type number 124).

Figure 2.79: Calculated heat capacity selection

3.4.2.

Fill out all necessary parameters in the dialog window which will appear. The

calculated heat capacity is specified by the discrete volume, material density, and specific

heat capacity (figure 2.80).


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Figure 2.80: Entering calculated heat capacity parameters

3.4.3.

The calculated heat capacity is defined (figure 2.81).

Figure 2.81: Calculated heat capacity in the model

2.6. Demonstration of different power sources

The following model will be used as the basis of the demonstration shown in figure

2.82.


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Figure 2.82: Thermal processes model available for demonstration in the subsystem

Time-dependent power types in ASONIKA-T. Node 1: constant power source of

0.5W; node 3: time-dependent power source set with pulse function; node 4: time-

dependent power source set with sinusoidal function; node 5: time-dependent power

source set with sinusoidal function (in out-of-phase to node 4); node 6: time-dependent

power source set with sawtooth function; node 7: time-dependent power source set withcomplex function.

As a result, we get power vs. time plot shown in figure 2.83.


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Figure 2.83: Power vs time plot constructed in accordance with the model shown in

figure 2.82.

2.7. Example of thermal modeling a floor cabinet

Purpose – to determine the average temperatures of printed circuit assemblies

(PCA) and the design of the radio-electronic cabinet as a whole.

Initial data – design drawings and the bill of materials which play an important role

in thermal analysis were obtained as initial data for calculation purposes.

One-story radio-electronic cabinet consists of three blocks BP, F, and FM shown in

figure 2.84.


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Figure 2.84: One-story radio-electronic cabinet design

The main heat generating components were identified, and the power source for

block F was set to the following values:

1. PCA FK – 1.235W;

2. PCA ANP – 0.806 W.

The power dissipated by the blocks BP and FM are 0.6 and 2 W respectively.

For calculation purposes, the ambient temperature was set to +52С. The cabinet

design is surrounded by air.

2.7.1. Analysis of thermal processes

Based on the data received, the model of thermal processes (MTP) for a radio-electronic cabinet was built and is shown in figure 2.84.

The model (see figure 2.85) has the following nodes:

Block BP:

1 – left wall of the enclosure;

2 – right wall of the enclosure;

3 – top wall of the enclosure;

4 – bottom wall of the enclosure;

5 – front wall of the enclosure;

BP F FM

Block F

Block BP Block FM


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6 – back wall of the enclosure;

7 – printed circuit assembly;

8 – ambient environment;

26 – air inside the block, to the left of the printed circuit assembly;

27 – air inside the block, to the right of the printed circuit assembly.

а)

b)


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в)

Figure 2.85: Model of thermal processes of a radio-electronic cabinet (Block F, Block

FM, Block BP)

Block F:

9 – left wall of the enclosure;10 – right wall of the enclosure;





15 – PCA ANP;16, 17 – aluminum layer between printed circuit assemblies;

18 – PCA FK;

28 – air inside of the block, to the left of PCA ANP;

29 – air inside of the block, to the right of PCA FK.

Block FM:

19 – left wall of the enclosure;

20 – right wall of the enclosure;



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25 – printed circuit assembly.

The model of the cabinet enclosure is represented as follows.

The walls of the enclosure in block BP interact with each other through conductive

heat transfer, creating branches 1-3, 1-4, 1-5, 1-6, 2-3, 2-4, 2-5, 2-6, 3-5, 3-6, 4-5, 4-6. In

addition, node 7 interacts with the front, back, top, and bottom walls through conduction.

All walls of the enclosure, except for the right wall, interact with the ambient environment

through radiation and convection, creating branches 1-8, 3-8, 4-8, 5-8, 6-8. Printed circuit

assembly interacts with the left and right walls through radiation, creating branches 7-1, 7-

2. Printed circuit assembly interacts through convection with the air inside the block,

creating branches 1-26, 3-26, 4-26, 5-26, 6-26, 7-26, and 2-27, 3-27, 4-27, 5-27, 6-27, 7-

27.

The relevant nodes are connected with branches, representing themselves as a power

source (7-0) and a temperature source (8-0).The walls in block F interact with each other through conductive heat transfer,

creating branches 9-11, 9-12, 9-13, 9-14, 10-11, 10-12, 10-13, 10-14, 11-13, 11-14, 12-13,

12-14. In addition, nodes 15, 16, 18 interact with the front, back, top, and bottom walls

through a conductive branch. Beside the left and the right walls, the walls of the enclosure

interact with the ambient environment through radiation and convection, creating branches

11-8, 12-8, 13-8, 14-8.

PCA ANP interacts with PCA FK through an aluminum layer with a conductive

branch, creating branches 15-16, 17-18.

PCA ANP interacts with the left wall through radiation, creating branch 9-15.

PCA ANP interacts with the air inside the block through convection, creating

branches 9-28, 11-28, 12-28, 13-28, 14-28, 15-28.

PCA FK interacts with the right wall through radiation, creating branch 18-10.

PCA FK interacts with the air inside the block through convection, creating

branches 10-29, 11-29, 12-29, 13-29, 14-29, 18-29.


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The relevant nodes were connected with branches representing themselves as power

sources (15-0, 18-0).

The walls of the enclosure in block FM interact with each other through a

conductive heat transfer, creating branches 19-21, 19-22, 19-23, 19-24, 20-21, 20-22, 20-

23, 20-24, 21-23, 21-24, 22-23, 22-24. In addition, node 25 interacts with the left wall

through a conductive branch. All walls of the enclosure, except for the left wall, interact

with the ambient environment through radiation, creating branches 20-8, 21-8, 22-8, 23-8,

24-8. Printed circuit assembly interacts with the right wall through radiation, creating

branch 25-20.

Node 25 was connected with a branch representing itself as a power source (25-0).

The blocks are connected with each other by conductive branches: 2-9 (blocks BP

and F), 10-19 (blocks F and P12-МII).

2.7.2. Simulation results

Thermal processes modeling were carried out at an ambient temperature of + 52° С.

As a result of the simulation, the temperature values in the nodes of the model were

obtained:

Node number Name Temper

ature

deg.С

Node

number

NameTemperature

deg.С

BLOCK BP

1 left wall 68 2 right wall 69

3 top wall 68 4 bottom wall 68

5 front wall 68 6 back wall 68

7

26

printed

circuit

72 8

27

ambient

environment

52


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assembly

69

air inside the

block, to the

right of the

printed

circuit

assembly

70

BLOCK F

9 left wall 69 10 right wall 69



15

17

28

PCA ANP

right side of

the

aluminum

layer

air inside the block to the

left of the

PCA ANP

70

70

69

16

18

29

left side of

aluminum

layer

PCA FK

air inside the

block, to theright of the

PCA FK

70

10770

BLOCK P12-

МII

19

left wall 71 20 wright wall 69



25 printed

circuit

assembly

71


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2.7.3. Results

As a result of these calculation, the initial data (boundary conditions) were obtained

for further analysis of the temperatures of radio-frequency components as part of printed

circuit assemblies of ANP and FK: 69 and 70 deg.С.

Comparison with the experiment shows that the error from modelling comes withing

2 deg.С or 3 % (calculated temperature of the enclosure 68 deg.С, experimental - 66

deg.С).


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3. SYSTEM ADMINISTRATOR'S GUIDE

3.1. Structure and launch of ASONIKA-T

Subsystem ASONIKA-T is located in ASONIKA-T directory and can be located on

any disk. The structure of the directory is shown in figure 3.1.

Figure 3.1: Directory structure of ASONIKA-T subsystem

The source data and results are located in Data directory.

Documentation related to ASONIKA-Т subsystem is located in Doc subdirectory. In

subdirectory Help, we can find help files which are called within the subsystem.

To launch ASONIKA-Т, enter into ASONIKA-Т catalog and load TeRa.exe file.

3.2. Saving the project


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If it is necessary to save a project and transfer it to another machine, then we need to

enter into Data directory and copy 2 files with the name of the project and .dat and .spt

extensions. Let’s say the project has a name Primer. Then we need to save Primer.dat and

Primer.spt files in the Data directory. The file of results will be saved with .rez extension.

4. BASIC PRINCIPLE METHODS OF CONSTRUCTION OF THERMAL

MODELS


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4.1. General information

In the study of REM temperature fields1, the method of electrothermal analogy

(ETA) is considered as the most common. This is due to the fact that calculation methods

for electric circuits have been advanced the most.

The essence of the ETA method comes from the arrangement of equivalent

electrical circuits which model the effects of heat transfer 2 or aerodynamics of the object –

models of thermal processes [4] and models of aerodynamical processes (МАP) [5] of the

object, and calculations of these circuits with the methods developed for complex

electrical circuits. This method is also called a grid.

The component is conditionally broken into isothermal volumes. This form of

isothermal volumes can be represented as, for example, RFC, a design element of a

component, in which it is necessary to determine the temperature, air volume inside the

block, ambient environment, the set of elements of the component, REM block as a whole,

part of an element, and so on. The partition depends on the design of the analyzed object,

the accuracy of calculated temperatures, the assumptions made for the analysis of heattransfer processes in the component, and so on.

The selected arbitrary isothermal volumes are represented as nodes of an electric

circuit. The greater the number of these isothermal volumes, the more accurate the model

of true temperature values will be in the component. However, this would increase the

size of the resulting electrical circuit.

Among these arbitrary isothermal volumes, we can select volumes with thermal

interactions. These include:

−

bordering volumes of one solid body (conduction3);

− volumes, interacting through air (free convection in a confined space4) [6];

− volumes in a radiant heat transfer (radiation5);

1 An REM temperature field consists of temperature values of its RFC as well as the temperature of different design

components, air inside the apparatus, and so on. The set of values of these temperatures defines a thermal condition

of an REM.2 Heat transfer theory – the science of heat propagation processes. There are three distinct types of heat transfer:conduction, convection, and radiation.3 Theory of heat transfer (conduction) called molecular transport of heat in a continuous medium.4 Free convection in a confined space is usually considered by analogy with the transfer of heat by conduction.


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−

the volume of the solid body and the volume of the surrounding air

(convection6);

− volumes of two solid bodies which are in contact (heat conduction through

contact) and so on.

Electrical circuit nodes which correspond with the interacting volumes, are

connected with each other with electrical resistors which represent thermal resistances that

correspond to the type of the heat exchange between these volumes.

If thermal energy is dissipated in a certain volume, then the current source is

included in the corresponding node of the electrical circuit.

For example, if a certain isothermal node has thermal dissipation power of 15 W,

then the current source of 15 A is included in the corresponding node of the electrical

circuit.

If for a certain node the temperature is given, then the voltage source is included in

the corresponding node of the electrical circuit. For example, for an isothermal volume of

the block with a 30 degree Celsius, there will be a corresponding node of the electrical

circuit with a 30 W voltage source.The heat capacity of the selected volume is modeled using electrical capacitance.

This is how we get electrical diagrams that model thermal processes of the specific

component design.

When modeling aerodynamic processes, it is also possible to use the analogy of

aerodynamic and electrical processes.

Thus, wind resistance similar to the electrical resistance, square air flow - current

source, pressure - voltage source. Thus, it is possible to construct an aerodynamical REM

design model in the form of an electrical circuit or in the form of aerodynamic circuit,

which is more understandable for specialists working in this field.

For convenience, we represent these electrical diagrams in the topological form (as a

graph) and refer to them as model of thermal processes or model of aerodynamic

5 Thermal radiation – the process of propagating heat with electromagnetic waves.6 Convection is the type of heat transfer through the moving “fluid” (gas or fluid) in space. The heat exchange

between the fluid or gas and the surface of the solid body is referred as convective heat transfer or heat exchange.


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processes. Meanwhile electrical resistors which represent heat exchange processes, will be

referred as thermal resistances; current sources – thermal power sources; voltage sources –

temperature sources; electrical resistors which r

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